Innate Immunity Flashcards Preview

IAHI Block 1 > Innate Immunity > Flashcards

Flashcards in Innate Immunity Deck (27):
1

Basic properties Of Innate Immune Defense

Provide physical and chemical barriers (epithelia and associated commensals)
Rely on phagocytosis
Produce inhospitable environment (granulocytes)

2

Which type of immunity evolved first?

Innate Immunity before Adaptive Immunity

3

Two Animal Classes with only Innate immunity

Echinodermata
Urochordata

4

What do all innate immune defenses have in common

They rel on mechanisms that exist before the infection, are capable of responding rapidly to microbes, and react in the same way to repeat infections

5

Hematopoietic Antigen Presenting Cells

Neutrophils
Monocytes
Macrophage
Dendritic Cell

6

Hematopoietic Granulocytes

Eosinophil
Basophil
Mast Cell

7

Non-hematopoietic Epithelia

Simple Squamous
Simple Cuboidal
Simple Columnar
Psuedostratified Columnar
Stratified Squamous
Stratified Columnar
Transitional

8

Antimicrobial peptides (AMPs)

Antibiotic proteins secreted by epithelial cells - Targeted toward microbe-containing environment via secretory pathway

9

Activity of AMPs

Small peptides that form pores through the membranes of multiple microbes including Gram (neg and pos) bacteria, fungi, protozoa and some viruses

10

Defensins

AMPs produced by polymorphonuclear leukocytes

11

Commensals (Associated with Epithelial Tissues)

1) Compete for resources with more virulent organisms
2) Produce their own AMPs
3) Keep innate immune cells in an "attentive" state
4) Lower vaginal pH

12

Phagocyte Subsets (Circulating or Tissue Resident)

Neutrophil - Circulating
Macrophage - Tissue resident, but originally derive from circulating monocytes
Dendritic Cells - Tissue resident, but also monocyte derived (Langerhans cells - skin)

13

PMNs (4 things)

First phagocyte to emigrate into an infected tissue
Short lived, dying within a few hours after reaching an infected site
Phagocytose microbes
Produce cytokines that attract other PMNs

14

PMN actions to kill microbes (4)

1) Fusion with lysosomes which contain lysozyme, defensins, lactoferrin, hydrolases, and myeloperoxidase (MPO)
2) MPO catalyzes the production of HOCl from H2O and Cl-
3) NADPH oxidase dependent production of superoxide
4) Inducible nitric oxide synthase (iNOS) catalyzes formation of NO from arginine

15

Macrophages

Tissue resident phagocytes that differentiate from circulating monocytes
"Activate" upon encountering a microbe

16

PAMP

Pathogen associated molecular pattern (Macrophages)

17

PRR

Pattern Recognition Receptors (Macrophages)

18

Activity of Activated Macrophages (4)

1) Have recognized a PAMP through one or more PRRs
2) Have enhanced phagocytosis
3) Secrete pro-inflammatory cytokines
4) Couple phagocytosis to "antigen presentation" on MHC Class II molecules (Critical to adaptive immune response)

19

The Coupling of phagocytosis to the Class II MHC Pathway

1) Peptides of varying length and sequence result from phago-lysosome digestion of microbes
2) These peptides accumulate in endocytic vesicles that fuse with Class II MHC containing vesicles
3) If Class II MHC binds one of the peptides, this complex moves to the cell surface where it can activate T-Cells

20

Dendrites are similar to Macrophages

1) They are more efficient at processing phagocytosed microbes into antigens (Ag) for Ag-presentation
2) Dendrites extend from their cell body to increase the surface area available for MHCII: T-cell interactions
3) They are more efficient at migrating to the draining lymph nodes for Ag-presentation to adaptive immune cells

21

DCs are referred to as immune sentinels for the following reasons (4)

1) Like macrophages, they constantly sample their environment
2) Unlike macrophages, DC's migrate via the lymphatics to the draining lymph node
3) Once in the lymph node, DC's come into greater contact with T and B cells, initiating the adaptive immune response
4) In addition to expressing high levels of MHCII, DCs increase their expression of co-stimulatory proteins

22

Co-Stimulatory proteins associated with Dendritic cells

CD80, CD86, CD40

23

Why don't phagocytes defend against pathogenic helminths?

They are too big to be phagocytosed

24

Three types of Granulocytes

Eosinophils
Basophils
Mast Cells

25

Granulocyte Qualities

1) Non-phagocytic
2) 3 types of Granulocytes are more similar to one another than the 3 types of phagocytes
3) Defend their host by releasing granule contents into the extracellular space (Degranulation)
4) Activated by Ag-bound IgE binding cell surface FceRI

26

Granule Secretions

Cytokines
Leukotrienes
Prostoglandins

27

Granule Exocytosis

Proteases - Disrupt parasite tegument (link to host)
Vasoactive amines (Histamine) - promote parasite expulsion from gut